Environmental Engineering Reference
In-Depth Information
Geothermal energy can be exploited at a range of temperatures, from lukewarm to
steaminghot(approximately30-300°C).Itiseasiesttoharnessinareas,suchasLarderello,
where magma (molten volcanic rock) pushes into the upper layers of the crust, allowing
temperatures of more than 1,000 degrees Celsius to occur at depths of less than 10
kilometres. Such areas are suited to hydrothermal convective systems, where the magma
heats groundwater circulating in permeable sedimentary rocks. The superheated water
turns to steam and reaches the surface through natural fissures in the rocks, giving birth to
geysers, fumaroles or hot springs. It is just a matter of capping the fissures and piping the
hot steam to a nearby power plant. In the absence of natural fissures, wells can be drilled
into the earth to retrieve the superheated water in much the same way as oil is extracted.
Figure 4.51.
Since Roman times, steam and hot springs emerging from the geologically
active ground of Larderello (Italy) has been used for hot water and bathing.
Source:
woodcut by Guglielmo Jervis.
